1. Field of the Invention
The present invention relates to a synchronous controller for synchronously drivingly controlling a plurality of axes.
2. Description of Related Art
Conventionally known is a synchronous controller that drivingly controls axes by moving a slave axis in a certain ratio to a motion amount of a master axis. In driving control by this synchronous controller such that a synchronous multiplying factor, a speed ratio between the master and slave axes, is changed, the speed of the slave axis sometimes may change suddenly, thereby shocking a machine to be subjected to synchronous control.
FIG. 1 is a diagram illustrating the way of changing the synchronous multiplying factor. In FIG. 1, the abscissa and ordinate axes represent the position of the master axis and a synchronous multiplying factor α of the slave axis, respectively. When the synchronous control is performed in a manner such that the slave axis is moved with the synchronous multiplying factor α=a with respect to the motion of the master axis in a block Ba, a command is issued to change the synchronous multiplying factor in a next block Bb so that the slave axis is driven with the synchronous multiplying factor α=b. In this case, the synchronous multiplying factor α is greatly changed from “a” to “b”, so that the speed of the slave axis suddenly changes. This change inevitably shocks the machine.
In a known system to cope with this, a motion command is outputted after being filtered lest a machine be shocked by a great speed change (change of a motion amount for a period concerned with respect to a motion amount for a preceding period), if any, as the synchronous multiplying factor is changed (see JP 2697399B).